Timing issues on a HH120

[dieselhorse 0]

I have a Tecumseh HH120 on a Massey garden tractor. Its had a knock since I got it, but it doesnt sound like a rod knock. If I listen with my long screwdriver, the sound is the loudest at the head bolts, when I check anywhere down lower its much more muffled. I can put the listening device right on the sides of the crank case, starter mounting bolts that are right into the side of the block and the sound is hardly there. But listen to the head bolts and you can hear a popping sound. I am guessing its pre ignition. This is the solid state ignition with the two trigger pegs inside the flyhweel to trip the spark. I am going to pull the flywheel to check its key and see if its worn or sheared a bit. Is there any other way to adjust spark timing? I have read the online book and its very vague to me. Tecumseh's are not my cup of tea so to speak. Thanks Mike

[Buzz 502]

Is this the manual you used? I got it off the MyTractorForum site. The ignition section starts on page 45.

http://www.mytractorforum.com/images/refer...o18castiron.pdf